Reticles are used in the semiconductor device manufacturing process and are typically formed of a quartz substrate with an opaque pattern formed on one of the surfaces of the quartz substrate. The opaque pattern is generally formed of chrome. The reticle is generally thin, flat and rectangular in shape. Reticles are used to produce patterns of very small dimensions on semiconductor substrates. The patterns may include device features with dimensions in the nanometer range. It is therefore important to keep the reticle very clean because any foreign contamination on the reticle can produce an irregular or distorted pattern. Several reticles are required to produce a single semiconductor device which includes multiple device levels. Since a pattern irregularity due to a dirty reticle at any level of device processing can cause device failure, it is even more critical to maintain each of the several reticles in clean condition to maximize device yield.
Many techniques are used for cleaning reticles and most of these techniques include disposing the reticle in a cleaning solution then rinsing the cleaning solution from the reticle. After the reticle is rinsed, a drying operation takes place. A shortcoming of the present technology is that the rectangular reticles are transported from station to station and then allowed to dry in carriers that orient the reticle with its opposed upper and lower edges essentially in a horizontal position. In conventional reticle carriers, this is true when the carrier is placed on a flat horizontal surface and also if the carrier is suspended from above. When the reticle dries in such a horizontal configuration, the rinsing liquid, typically deionized water, will remain on the top edge of the reticle as well as along the bottom edge of the reticle. When allowed to dry in the ambient air of a semiconductor device fabrication facility, the deionized water remains on the top edge and bottom edge of the horizontally positioned reticle, even after 30 minutes of drying. This residual deionized water is undesirable because it can potentially move to the surface of the reticle, distorting the pattern, when the reticle is eventually maneuvered. If a turbulent airflow is used to remove the residual water, the turbulent airflow itself and/or the disbursing deionized water can result in particles or water droplets on the reticle surface and these particles or water droplets can cause pattern defects and device failure.
It would therefore be desirable to provide a reticle cleaning and drying method and apparatus that cleans and dries the reticle without leaving contaminating particles or residual water.